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Proceedings Paper

Wavefront sensing and the active optics system of the dark energy camera
Author(s): Aaron Roodman; Kevin Reil; Chris Davis
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Paper Abstract

Wavefront sensing and the Active Optics System (AOS) of the Dark Energy Camera (DECam) at the CTIO 4-meter Blanco telescope are described. DECam utilizes four pairs of intra/extra-focal CCDs located on the edge of the focal plane for wavefront sensing. Out-of-focus stars are selected, individually fit to a pupil plane Zernike expansion and then collectively analyzed in the time between exposures. The AOS uses this information to control the prime-focus camera’s five degrees of freedom. The AOS is now in routine use, operating with unsupervised control of the focus and camera alignment, both for the Dark Energy Survey and community observing. The design, commissioning and operation of the AOS along with results from the wavefront measurements are described. In particular, wavefront measurements of the complete optical system, including primary mirror aberrations, are shown. Lastly, preliminary results using these wavefront measurements to model the DECam point spread function are presented.

Paper Details

Date Published: 10 September 2014
PDF: 18 pages
Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 914516 (10 September 2014); doi: 10.1117/12.2056904
Show Author Affiliations
Aaron Roodman, SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
Kevin Reil, SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
Chris Davis, SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)


Published in SPIE Proceedings Vol. 9145:
Ground-based and Airborne Telescopes V
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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